Quantitative structural comparisons of heme protein crystals and solutions using resonance Raman spectroscopy

Resonance Raman difference spectra have been used to compare crystal and solution samples of metmyoglobin (metMb), deoxymyoglobin (deoxyMb), and cytochrome P450. At pH 6.0, the frequency shifts of the heme core size sensitive bands v2, v3, and v4 were determined to be less than 0.3, 1.0, and 0.3 cm-1, respectively, for metMb and to be less than 1.0, 1.0, and 0.3 cm-1, respectively, for deoxyMb. This shows that the heme core size differences between the crystal and solution conformations are less than 0.002 A for metMb and less than 0.003 A for deoxyMb. These results disagree with a recent extended X-ray absorption fine structure study [Zhang, K., Chance, B., Reddy, K. S., Ayene, I., Stern, E. A., & Bunker, G. (1991) Biochemistry 30, 9116-9120] which claims that a 0.05-A difference exists in the average iron-ligand distance between the crystalline and solution forms of metMb at pH 6.5. At pH 8.5, metMb solution samples change gradually from a predominantly high-spin to a predominantly low-spin species as the ammonium sulfate concentration is increased to the level found in the crystal mother liquor. No Raman frequency shifts are found between the crystal and solution forms of metMb at pH 8.5 when the ammonium sulfate concentrations are equal. On the other hand, for deoxyMb, we find a significant alteration in the 220/240-cm-1 line shape and relative intensities, suggesting that some histidine-heme perturbation takes place upon crystallization.(ABSTRACT TRUNCATED AT 250 WORDS)

[Gastric mucosal blood flow and blood viscosity in patients with diabetes]

For the study of the microcirculatory disturbance of the digestive tract in patients with diabetes, 41 cases with non-insulin dependent diabetes mellitus (NIDDM) were selected (mean age 53.9 Yrs., 22 male/19 female). Of these patients 9 were without complication, and 32 with complications. Gastric mucosal blood flow (GMBF) was determined at 14 points of laser and greater curvature, anterior and posterior wall of antrum, angle and corpus of stomach, pylorus and anterior wall of duodenum with laser Doppler flowmetry (PF2). Results showed that the mean value of the 14 points of GMBF in 41 patients with NIDDM was 2.81 +/- 0.15(V, mean +/- s mean), which was significantly lower than that of 11 normal subjects (4.77 +/- 0.29V, P < 0.001). The mean GMBF of 8 cases of NIDDM without gastric disease was 2.92 +/- 0.28V, which was also lower than that of normal control (61.2% of normal value, P < 0.001). The GMBF in 27 cases of diagnosed chronic superficial gastritis (CSG 2.79 +/- 0.15V) was lower than the GMBF of 63 CSG patients without NIDDM (3.23 +/- 0.12V, P < 0.05). The viscosity of blood and plasma was determined with NAAKE viscometer in 26 patients with NIDDM. It was found that the blood viscosity was significantly higher than that of the normal control, and the plasma viscosity was also increased but without statistic significance. Results showed that the GMBF of NIDDM was significantly lower than that of the normal subjects or CSG patients without diabetes. It implied that the visceral microcirculatory disturbance also involved the digestive system leading to the GMBF decrease.(ABSTRACT TRUNCATED AT 250 WORDS)

Tissue-specific expression of phospholipase C encoded by the norpA gene of Drosophila melanogaster

Mutations in the norpA gene of Drosophila melanogaster severely affect the light-evoked photoreceptor potential with strong mutations rendering the fly blind. Molecular cloning of the norpA gene revealed that it encodes phosphatidylinositol-specific phospholipase C, which enzymes play a pivotal role in one of the largest classes of signaling pathways known. We have used Northern analysis, Western blots, phospholipase C activity assays, and immunohistochemical staining of tissues to examine the tissue-specific expression of the norpA gene and found that it is expressed in a variety of tissues besides the eye. Hybridization of norpA cRNA probe to blots of poly(A+) RNA reveals that the gene encodes at least four transcripts: a 7.5-kilobase (kb) transcript that is expressed in eye and 6.5-, 5.5-, and 5.0-kb transcripts that are expressed in adult body or early stages of development. Antiserum generated against the major gene product of norpA recognizes a 130-kDa protein that is abundant in eyes but severely reduced or absent in norpA mutants, a result which is consistent with previous conclusions that the norpA gene encodes an essential component of the visual system. However, the norpA antiserum also recognizes a 130-kDa protein in adult legs, thorax, and male abdomen, but not female abdomen. These localizations are supported by results of phospholipase C activity assays which show that the norpA mutation reduces phospholipase C activity in each of the tissues in which norpA protein can be detected. Furthermore, immunohistochemical staining of tissue sections with the norpA antiserum demonstrates that the norpA protein is abundant in the retina and ocelli and is present to a lesser extent in the brain and thoracic nervous system. Since some of the above mentioned tissues that express norpA (such as thorax, legs, and abdomen) have no known photoreceptor tissue, we conclude that the norpA gene product is also likely to have a role in signaling pathways other than phototransduction.

Tissue tolerance to pelvic intraarterial chemoembolization with cisplatin-lipiodol suspension

Tissue tolerance to pelvic intraarterial chemoembolization with cisplatin-lipiodol suspension was studied in rabbits. Cisplatin (3 mg/kg) was used with different doses of lipiodol (0.0, 0.1, 0.2, and 0.3 ml/kg). Cisplatin-lipiodol suspension was injected into the umbilical artery through a long polyethylene catheter. Local tissue concentration of platinum was increased with lipiodol, while that in the liver, heart, and kidneys was reduced. Tissue retention of platinum was linearly related to the dosage of lipiodol. With a single dose of 0.2 ml/kg lipiodol, only slight degeneration and sparse hemorrhage were observed without necrosis.

Inhibition of cell proliferation by p107, a relative of the retinoblastoma protein

The cellular protein p107 shares many structural and biochemical features with the retinoblastoma gene product, pRB. We have isolated a full-length cDNA for human p107 and have used this clone to study the function of p107. We show that, like pRB, p107 is a potent inhibitor of E2F-mediated trans-activation, and overexpression of p107 can inhibit proliferation in certain cell types, arresting sensitive cells in G1. Several experiments, however, showed that growth inhibition by pRB and p107 did not occur through the same mechanism. First, in the cervical carcinoma cell line C33A, p107 was able to block cell proliferation, whereas pRB could not, even though both proteins were potent inhibitors of E2F-mediated transcription in this cell line. Second, growth arrest by pRB and p107 was rescued differentially by various cell cycle regulators. Third, some mutants of p107 that cannot associate with adenovirus E1A were still able to inhibit cell proliferation, whereas analogous mutants in pRB are known to be unable to block cell growth. Together, these results suggest a biological role of p107 that is related, but not identical, to that of pRB.

[Distribution of the intermediate filaments in rat Sertoli cells: an electron microscopic study]

The distribution of intermediate filaments (IFs) in the Sertoli cells of rat testis was studied under a transmission electron microscope. The results showed that IFs in Sertoli cells were centrally arranged around the nucleus in a criss-cross manner. From the perinuclear region the IFs had widespread extensions and were connected with the following structures: 1) with the mitochondria, Golgi apparatus, endoplasmic reticulum and other subcellular structures; 2) with the desmosome-like and hemi-desmosome-like junctions with adjacent Sertoli and spermatogenic cells; 3) with the microfilaments (MFs) in the ectoplasmic specialization (ES) surrounding the head of elongated stage I-V; spermatids; 4) with the MFs in ES between adjacent Sertoli cells. In conclusion, IFs form a delicate intracellular network in Sertoli cell with its center in the perinuclear region and stretching and connecting with many subcellular structures in the cytoplasm and cell membrane.

A developmentally regulated program restricting insolubilization of elastin and formation of laminae in the fetal lamb ductus arteriosus

BACKGROUND

The ductus arteriosus (DA) is a fetal vessel in which the elastic laminae fail to assemble normally in late gestation. This feature is associated with the development of intimal cushions, structures that partially occlude the DA lumen and assure that the vessel will close completely when it constricts postnatally.

EXPERIMENTAL DESIGN

We studied the fetal lamb DA at two different gestational time-points, 100 days before, and 138 days coincident with intimal cushion formation (term = 145 days) to establish the ultrastructural basis for the 'disassembly' of elastic laminae apparent on light microscopy and to determine further whether the mechanism was due to increased elastolytic activity, decreased synthesis of tropoelastin, or impaired insolubilization of tropoelastin.

RESULTS

Morphometric ultrastructural analyses of tissue from the 138-day gestation fetal lambs revealed that the volume density of elastin in the DA vessel wall was only 40% of that in the aorta (Ao) and 50% of that in the pulmonary artery (PA). Moreover, only 16% of the elastin present contributed to the formation of laminae when compared to 80% in the Ao and 50% in the PA. Despite the morphologic appearance of 'fragmented' elastin, there was no evidence of increased elastolytic activity in the DA at either gestational time-point as judged by solubilization of a [3H] elastin substrate. The reduced elastin apparent was morphologically accompanied by an increase in soluble (tropo) elastin in DA compared with Ao and PA, as measured by enzyme linked immunosorbent assay, in tissue from both 100- and 138-day gestation lambs. Lack of differences in tropoelastin mRNA levels when comparing the 3 vessels suggested that the enzyme linked immunosorbent assay measurements reflected increased DA tropoelastin accumulation owing to lack of insolubilization rather than an increase in synthesis. Reduced insolubilization of newly synthesized elastin was evident in the DA compared with the Ao at 100 days gestation and in the DA compared with both Ao and PA at 138 days gestation in association with reduced desmosine levels.

CONCLUSIONS

The mechanism of the decrease in tropoelastin insolubilization was unrelated to lysyl oxidase activity in the tissue and represents a unique developmental program.

[Typing on 5'-terminal noncoding region of hepatitis C virus genome with restrict endonuclease]

We reported typing of the 5'-terminal noncoding region of HepCV genome in 219 patients with hepatitis C using restrict endonuclease. These patients came from different areas of China. The infective percentage of HCV type II was 83%, type III 14%, and mixed type II and III (II/III) 2%. It is indicated that type III and II/III. The constituent rate of HCV subgenome type in different areas was not significantly different.

Aging changes in the beta-endorphin neuronal system in the preoptic area of the C57BL/6J mouse: ultrastructural analysis

In hypothalami of aging rodents, beta-endorphin (beta-EP) neuron number and content are reduced. The objectives of this study were: first, to analyze ultrastructurally the population of neuronal elements in a selected region of the preoptic area (POA) in young and old mice; second, to study the beta-EP neuronal system in the same region to determine whether or not this population remains stable with age. Vibratome sections from the most caudal POA through the diagonal band of Broca were examined by light microscopy and immunocytochemistry in mature, cycling (5-6 months old) and old, acyclic, disease-free (24-26 months old) mice. A subset of beta-EP-like perikarya and associated structures was observed in the periventricular POA. When this subregion was examined at the ultrastructural level, there was a significant decrease in the number of recipient dendrites [3.78 +/- 0.04 SEM/micron 2 young vs. 0.82 +/- 0.03/micron 2 old; p < 0.007, analysis of variance (ANOVA)], but a significant increase in the number of nonmyelinated axons (20.0 +/- 2.6/micron 2 young vs. 26.8 +/- 0.7/micron 2 old; p < 0.05). Immunolabeled terminals that contained a synapse comprised 2.56 +/- 0.08% of all terminals with synapses in young mice but only 0.34 +/- 0.04% in old ones when corrected for surface area examined (p < 0.03). A significant age-related loss was also observed in the nonmyelinated beta-EP-labeled axon population (1.50 +/- 0.10% young vs. 0.40 +/- 0.01% old; p < 0.009, ANOVA). We conclude that there are critical changes in the microenvironment of the POA in old, noncycling female mice that are likely to affect neuron function.

Synthesis and cytotoxic evaluation of some 6-arylidene-2-(alpha-hydroxyamino-alpha-arylmethyl)cyclohexanone oximes and related compounds

Reaction of 2,6-bis-(phenylmethylene)cyclohexanone (1) with a 4-molar excess of hydroxylamine hydrochloride and sodium acetate to produce the corresponding oxime 2 gave rise to 2-(alpha-hydroxyamino-alpha-phenylmethyl)-6-phenylmethylenecyclohexan one oxime (5a), whose structure was deduced from high-resolution proton nuclear magnetic resonance spectroscopy and confirmed by X-ray analysis. Compound 2 was eventually prepared from 1 with hydroxylamine per se and not with a mixture of hydroxylamine hydrochloride and sodium acetate. Ten analogues of 5a, namely 5b-5k, were prepared and evaluated for cytotoxicity. Six of the 11 compounds in series 5, as well as 1, showed activity in the 240-950 microM range against murine mammary EMT6 cells. Series 5 was also examined for cytotoxicity in an in vitro screen conducted by the National Cancer Institute with approximately 54 cell lines, and four compounds demonstrated selective toxicity toward various groups of tumors.

Albumin in the cornea is oxidized by hydrogen peroxide

The action of hydrogen peroxide on soluble proteins of the rat cornea has been evaluated. Two major corneal proteins are found to be oxidized by 10 mM hydrogen peroxide. Protein sequence and antibody recognition has shown one of the proteins to be albumin. Treatment of pure rat or human albumin with hydrogen peroxide oxidizes the protein and decreases its affinity for its antibody. Because albumin is a major protein in the cornea, its ready oxidation suggests that a role for albumin in this tissue may be to act as a native antioxidant, scavenging hydrogen peroxide and thus preventing more extensive damage by this toxin. These data are relevant to the evaluation of the safety of contact lens disinfectants containing hydrogen peroxide and suggest that further study of the action of this oxidant is warranted.

Functional organization of enhancer (ENII) of hepatitis B virus

A new enhancer ENII, located in the X open reading frame and immediately upstream of the core gene promoter, has recently been identified in the genome of hepatitis B virus. We have studied the functional constituents of this new enhancer in different cell lines. ENII can be divided into two functional elements, A and B, corresponding to two major binding sequences for nuclear protein factors. Element A alone gave very low activity; however, it was a modulatory element important for cell-type specificity. Element B was shown to be the basic functional element of ENII, which retained about 70% of the enhancer activity of the complete ENII in HepG2 cells. Element B can be further dissected into three subunits, B1, B2, and B3, which act synergistically. A 52-bp sequence is identified as the core sequences of element B. A model for the mechanism of ENII function is proposed.

Bactericidal activity of peroxynitrite

Peroxynitrite is a strong oxidant formed by macrophages and potentially by other cells that produce nitric oxide and superoxide. Peroxynitrite was highly bactericidal, killing Escherichia coli in direct proportion to its concentration with an LD50 of 250 microM at 37 degrees C in potassium phosphate, pH 7.4. The apparent bactericidal activity of a given concentration peroxynitrite at acidic pH was less than that at neutral and alkaline pH. However, after taking the rapid pH-dependent decomposition of peroxynitrite into account, the rate of the killing was not significantly different at pH 5 compared to pH 7.4. Metal chelators did not decrease peroxynitrite-mediated killing, indicating that exogenous transition metals were not required for toxicity. The hydroxyl radical scavengers mannitol, ethanol, and benzoate did not significantly affect toxicity while dimethyl sulfoxide enhanced peroxynitrite-mediated killing. Dimethyl sulfoxide is a more efficient hydroxyl radical scavenger than the other three scavengers and increased the formation of nitrogen dioxide from peroxynitrite. In the presence of 100 mM dimethyl sulfoxide, 60.0 +/- 0.3 microM nitrogen dioxide was formed from 250 microM peroxynitrite as compared to 2.0 +/- 0.1 microM in buffer alone. Thus, formation of nitrogen dioxide may have enhanced the toxicity of peroxynitrite decomposing in the presence of dimethyl sulfoxide.

Peroxynitrite formation from macrophage-derived nitric oxide

Peroxynitrite formation by rat alveolar macrophages activated with phorbol 12-myristate 13-acetate was assayed by the Cu,Zn superoxide dismutase-catalyzed nitration of 4-hydroxyphenylacetate. The inhibitor of nitric oxide synthesis N-methyl-L-arginine prevented the Cu,Zn superoxide dismutase-catalyzed nitration of 4-hydroxyphenylacetate by stimulated macrophages, while Cu-depleted Zn superoxide dismutase did not catalyze the formation of 3-nitro-4-hydroxyphenylacetate either in vitro or in the presence of activated macrophages. The rate of phenolic nitration by activated macrophages was 9 +/- 2 pmol x 10(6) cells-1 x min-1 (mean +/- STD). Only 8% of synthetic peroxynitrite was trapped by superoxide dismutase, which suggested that the rate of peroxynitrite formation may have been as high as 0.11 nmol x 10(6) cells-1 x min-1. This upper estimate was consistent with N-methyl-L-arginine increasing the amount of superoxide detected with cytochrome c by 0.12 nmol x 10(6) cells-1 x min-1. The rate of nitrite and nitrate accumulation was 0.10 +/- 0.001 nmol x 10(6) cells-1 x min-1, suggesting that the majority of nitric oxide produced by activated macrophages may have been converted to peroxynitrite. The formation of a relatively long lived, strong oxidant from the reaction of nitric oxide and superoxide in activated macrophages may contribute to inflammatory cell-mediated tissue injury.

Kinetics of superoxide dismutase- and iron-catalyzed nitration of phenolics by peroxynitrite

Superoxide dismutase and Fe3+EDTA catalyzed the nitration by peroxynitrite (ONOO-) of a wide range of phenolics including tyrosine in proteins. Nitration was not mediated by a free radical mechanism because hydroxyl radical scavengers did not reduce either superoxide dismutase or Fe3+EDTA-catalyzed nitration and nitrogen dioxide was not a significant product from either catalyst. Rather, metal ions appear to catalyze the heterolytic cleavage of peroxynitrite to form a nitronium-like species (NO2+). The calculated energy for separating peroxynitrous acid into hydroxide ion and nitronium ion is 13 kcal.mol-1 at pH 7.0. Fe3+EDTA catalyzed nitration with an activation energy of 12 kcal.mol-1 at a rate of 5700 M-1.s-1 at 37 degrees C and pH 7.5. The reaction rate of peroxynitrite with bovine Cu,Zn superoxide dismutase was 10(5) M-1.s-1 at low superoxide dismutase concentrations, but the rate of nitration became independent of superoxide dismutase concentration above 10 microM with only 9% of added peroxynitrite yielding nitrophenol. We propose that peroxynitrite anion is more stable in the cis conformation, whereas only a higher energy species in the trans conformation can fit in the active site of Cu,Zn superoxide dismutase. At high superoxide dismutase concentrations, phenolic nitration may be limited by the rate of isomerization from the cis to trans conformations of peroxynitrite as well as by competing pathways for peroxynitrite decomposition. In contrast, Fe3+EDTA appears to react directly with the cis anion, resulting in greater nitration yields.

Peroxynitrite-mediated tyrosine nitration catalyzed by superoxide dismutase

Peroxynitrite (ONOO-), the reaction product of superoxide (O2-) and nitric oxide (NO), may be a major cytotoxic agent produced during inflammation, sepsis, and ischemia/reperfusion. Bovine Cu,Zn superoxide dismutase reacted with peroxynitrite to form a stable yellow protein-bound adduct identified as nitrotyrosine. The uv-visible spectrum of the peroxynitrite-modified superoxide dismutase was highly pH dependent, exhibiting a peak at 438 nm at alkaline pH that shifts to 356 nm at acidic pH. An equivalent uv-visible spectrum was obtained by Cu,Zn superoxide dismutase treated with tetranitromethane. The Raman spectrum of authentic nitrotyrosine was contained in the spectrum of peroxynitrite-modified Cu,Zn superoxide dismutase. The reaction was specific for peroxynitrite because no significant amounts of nitrotyrosine were formed with nitric oxide (NO), nitrogen dioxide (NO2), nitrite (NO2-), or nitrate (NO3-). Removal of the copper from the Cu,Zn superoxide dismutase prevented formation of nitrotyrosine by peroxynitrite. The mechanism appears to involve peroxynitrite initially reacting with the active site copper to form an intermediate with the reactivity of nitronium ion (NO2+), which then nitrates tyrosine on a second molecule of superoxide dismutase. In the absence of exogenous phenolics, the rate of nitration of tyrosine followed second-order kinetics with respect to Cu,Zn superoxide dismutase concentration, proceeding at a rate of 1.0 +/- 0.1 M-1.s-1. Peroxynitrite-mediated nitration of tyrosine was also observed with the Mn and Fe superoxide dismutases as well as other copper-containing proteins.

The Escherichia coli rna gene encoding RNase I: sequence and unusual promoter structure

A clone containing the Escherichia coli rna gene encoding the nonspecific endoribonuclease, RNase I, was isolated and sequenced. The sequence of the 1070-nucleotide (nt) fragment agreed completely with that of a rna clone recently reported by Meador and Kennell [Gene 95 (1990) 1-7]. The transcription start point (tsp) of rna was identified using primer extension analysis, and its promoter sequence was established by comparison of RNase I expression levels in various deletion mutants. Our results indicate that the rna promoter is highly unusual. Its -35 region shows a poor match to the consensus sequence, and moreover, it is located within a stem-loop structure that apparently is a Rho-independent transcription termination site for an upstream gene.

Clinical and experimental studies on tong yu ling in the treatment of diabetic hyperlipemia

72 diabetes mellitus patients (70 cases non-insulin-dependent) were treated routinely with D860. After one month, cases with persisting hyperglycemia and hyperlipemia were randomly divided into Group A to be treated with D860 plus Tong Yu Ling (TYL), and Group B to continue treatment with D860 alone, while Group C, comprising cases with persisting hyperlipemia only, were treated with TYL alone. Therapeutic results showed that of the total 50 cases of Group A and C, 26 were markedly improved, 14 improved, and 10 cases ineffective. The antihyperlipemic effect was pronounced in Group A, where the blood cholesterol, beta-lipoprotein and triglyceride showed remarkable decline, less pronounced in Group C, and insignificant in Group B. Experiments in rat models of non-insulin-dependent diabetes demonstrated that TYL was markedly effective in treating hyperlipemia.

Human erythrocyte protein 4.2: isoform expression, differential splicing, and chromosomal assignment

Human protein 4.2 (P4.2) is a major membrane skeletal protein in erythrocytes. Individuals with P4.2 deficiency exhibit spherocytosis and experience various degrees of hemolytic anemia, suggesting a role for this protein in maintaining stability and integrity of the membrane. Molecular cloning of P4.2 cDNAs showed that P4.2 is a transglutaminaselike molecule in erythrocytes but lacks the essential cysteine for cross-linking activity. Two cDNA isoforms have been identified from a human reticulocyte cDNA library, with the long isoform containing a 90-base pair (bp) in-frame insertion encoding an extra 30 amino acids near the N-terminus. Characterization of the P4.2 gene suggests differential splicing as the mechanism for generating these two cDNA isoforms. The donor site for the short isoform (P4.2S) agrees better with the consensus than the donor site for the long isoform (P4.2L) does. Expression of P4.2L was detected by a long-isoform-specific antibody raised against a peptide within the 30-amino acid insert. Western blot analyses showed P4.2L to be a minor membrane skeletal protein in human erythrocytes with an apparent molecular weight (mol wt) of approximately 3 Kd larger than the major protein 4.2, P4.2S. By in situ hybridization of a full-length 2.4-kilobase (kb) cDNA to human metaphase chromosomes, the gene for P4.2 was mapped to bands q15-q21 of chromosome 15, and it is not linked to the gene for coagulation factor XIIIa (plasma transglutaminase, TGase).

Conformational interconversion in protein crystals

We present evidence that the structure of carbonmonoxy myoglobin crystals can be altered by lowering the pH. This structural change is monitored by the characteristic Fe-CO Raman modes at 508 and 491 cm-1 and is thought to involve a localized distal pocket transition from a "closed" conformation at pH 7 to a more "open" conformation at pH 4. These changes take place in the crystal without loss of intensity of a conformationally sensitive Raman mode at 252 cm-1 that signals a partial unfolding of the globin structure in solution. Quantitative studies, which monitor the open and closed populations as a function of laser photolysis, demonstrate that the interconversion rates (k+/-) in solution at 298 K are fast compared to the photolysis and CO entry rates (i.e. k+/- much greater than 10(3) s-1), while in frozen samples the interconversion is much slower than the experimental time scale (minutes). Since the open conformation is a minority species at pH 7, rapid exchange in aqueous solution is a necessary condition for this species to play a functional role. In the crystal, the interconversion rates are slowed compared to solution and begin to approach the photolysis rate (i.e. k+/- approximately 10(3) to 10(4) s-1). This indicates that the barriers for conformational exchange are increased in the crystal environment, compared to the solution, apparently due to the packing forces of the surrounding molecules. X-ray and neutron diffraction studies of MbCO crystals at high and low pH are needed to characterize the details of the structural changes and to test the hypothesis that closed and open distal pocket structures are associated with the 508 and 491 cm-1 Fe-CO modes.

Molecular cloning of the cDNA for the catalytic subunit of human DNA polymerase delta

The cDNA of human DNA polymerase delta was cloned. The cDNA had a length of 3.5 kb and encoded a protein of 1107 amino acid residues with a calculated molecular mass of 124 kDa. Northern blot analysis showed that the cDNA hybridized to a mRNA of 3.4 kb. Monoclonal and polyclonal antibodies to the C-terminal 20 residues specifically immunoblotted the human pol delta catalytic polypeptide. A multiple sequence alignment was constructed. This showed that human pol delta is closely related to yeast pol delta and the herpes virus DNA polymerases. The levels of pol delta message were found to be induced concomitantly with DNA pol delta activity and DNA synthesis in serum restimulated proliferating IMR90 cultured cells. The human pol delta gene was localized to chromosome 19 by Southern blotting of EcoRI digested DNA from a panel of rodent/human cell hybrids.

Histological examination of the auricular cartilage and pseudocyst of the auricle

In our histological examination of 42 ears (auricles) which were taken from 18 fetus and three adults, the intracartilaginous fibrous tissue with blood vessels and lymphatics were found in 12 ears and interruption of the auricular cartilage in 22 ears. The intracartilaginous connective tissue with blood vessels and lymphatics were linked together with the connective tissue outside the auricular cartilage in other sections. These findings support the hypothesis of congenital embryonic dysplasia as the origin of the formation of pseudocyst of the auricle.

[Distribution of microfilaments in rat Sertoli cells in vivo and in vitro]

The distribution of microfilaments (MFs) in rat Sertoli cells in vivo and in vitro was studied with electron microscopy and the TRITC-phalloidin staining method. The results revealed the following: The MFs of the Sertoli cells in vivo are arranged in bundles just beneath the cell membrane. MF bundles may form a band-like structure circumscribing the basal region of each Sertoli cell. The filaments and bundles are parallel with each other and their arrangement is symmetrical on the opposite sides of two adjacent Sertoli cell membranes. In vitro, the arrangement and distribution of MF bundles are closely related with the living and spreading state of the cell. In a fully spread cell, MFs bundles are arranged in parallel just beneath the cell membrane. We conclude that MFs in rat Sertoli cells are mainly arranged in bundles and stretched beneath the cell membrane. They may play an important role in maintaining the shape of the cell and the blood-testis barrier.

[Composition of essential oil from inflorescences of Rhaponticum uniflorum (L.) DC]

The essential oil was extracted from the inflorescences of Rhaponticum uniflorum which are used as a Mongolian drug. 30 compounds in the oil were identified by GC-MS and their percentages were determined by GC.

Energy and dose-rate dependence of neoplastic transformation and mutations induced in mammalian cells by fast neutrons

Since our original observation that low-dose, low-dose-rate JANUS neutrons produced more transformation in C3H 10T1/2 cells than equivalent doses at high dose rate (Hill, Buonaguro, Myers, Han, and Elkind, Nature 298, 67-69, 1982), there have been many reports on the dose-rate dependence of a variety of high-LET radiations. Some of these have qualitatively supported our original and subsequent observations, and some have found no evidence for a dose-rate effect. Thus there remain questions about the generality, size, tissue specificity, and reproducibility of these observations. Furthermore, there are no well-established mechanistic descriptions or observations to account for such effects. In this report studies are presented using a range of neutron energies produced by the UCLA cyclotron from 12- to 46-MeV protons on beryllium. In particular, emphasis is placed on comparing results between energies for neoplastic transformation and mutation end points, and preliminary data are presented on the molecular and mechanistic aspects of neutron-induced damage.

[The effect of plaque fluid on demineralization of enamel powder]

The aim of this study was to explore any substance in dental plaque which might affect the demineralization of enamel. Plaque fluid was prepared by centrifugation of pooled plaque from 56 young adults without periodontal diseases. Enamel was separated from healthy teeth of adolescents and crushed into powder. The enamel powder was treated separately by plaque fluid and synthetic plaque fluid (as a control, with similar calcium, fluoride content and pH as the natural). After this, the enamel powder was washed with PBS. Both the plaque fluid-treated and synthetic plaque fluid-treated enamel powder were demineralized by mixed organic acid (pH 4.5). The calcium content in both plaque fluids, PBS and organic acid after treatment with enamel powder was analysed by atomic absorption spectrophotometer. The results showed that there was no promoting effect in plaque fluid on demineralization of enamel, but, on the other hand, some protecting action was observed which might contribute to the presence of proteins in plaque fluid.

[The influence of vagotomy on stomach endocrine cells in rat]

The effects of unilateral truncal vagotomy (UTV) and bilateral truncal vagotomy (BTV) on antrum EC cells, G cells and oxyntic gland area argyrophil cells were studied in rats by using immunohistochemistry processes, Grimelius argyrophil stain and microscopic image analysis technique.

RESULTS

(1) In UTV animals, two weeks postoperation, the sectional areas of EC cells were significantly smaller in denervated side than In the other side (17%, P less than 0.05). In the innervated side of antrum, the sectional areas of EC cells were larger than those in controls (13.5%, P less than 0.05). But, five weeks after UTV, the size of EC cells was not significantly different in all animals. These suggest that vagal denervation can inhibit relatively the functional activity in a short period, but this inhibition could be compensated later. (2) There were no morphological changes in G cells of UTV rats. In BTV animals, the quantity of G cells in antrum increased by 36.2% (P less than 0.05) and their sectional areas were larger than those in sham by 26.2% (P less than 0.05). These indicate that the function of G cells is more active in BTV animals and the functional change of G cells is related to the pH value of gastric juice. (3) In UTV rats, the oxyntic gland area argyrophil cells (ECL cells are dominant) were significantly reduced in two weeks (26.8%, P less than 0.01) and in five weeks (20.1%, P less than 0.05) in denervated side after UTV. The cells became smaller also. These suggest that vagus can influence the function, proliferation and growth of ECL cells.

O6-methylguanine-DNA methyltransferase and human cancer chemotherapy

Two kinds of human tumor cell strains having different activity of O6-methylguanine-DNA methyltransferase (O6-MT) were transplanted into nude mice. Then the mice were injected intraperitoneally with bifunctional alkylating agent 1-(4-amino-2-methyl-5-pyrimidinyl) methyl-3-(2-chloroethyl)-3-nitrosourea hydrochloride (ACNU). The tumors with low O6-MT activity were quickly suppressed or cured. The result suggests that some tumors, if provisionally determined with low O6-MT activity, might be efficiently cured by treatment with ACNU. This probably opens a new way for human cancer chemotherapy.

[Hemolytic reaction resulting from propafenone administration]

Although adverse reactions of many kinds caused by propafenone have been observed, yet there has been no documented report of hemolytic reaction. Four episodes of hemolytic reaction in three patients receiving intravenous propafenone were reported. These reactions took place a few hours after the administration and one of the episodes was complicated with acute left ventricular heart failure and shock. Cessation of propafenone administration together with relevant therapeutic measures tide the patients over and hemolysis disappeared in several hours. Toxicological examination revealed no physical or chemical deterioration and biological contamination of the remaining medication and no such reaction was noted when the drug of the same batch was given to other patients. It is considered that the hemolytic episodes were related to allergic constitution of the patients. Judging from the clinical manifestations, these episodes were hemolytic reactions of immune complex type.

Effective endothelialization of polyurethane surfaces. Response to shear stress and platelet adhesion

Biomer and Mitrathane are thromboresistant polyurethane ureas that are suitable for coating artificial valves. Degeneration of the surface coatings, however, does occur over time, and in experimental animal studies adherent thrombi have been observed as a complication. In this study, morphometric techniques applied to scanning electron microscopy were used to assess whether vascular endothelial cells harvested from jugular veins of fetal lambs could be grown to confluence on these polyurethane surfaces, whether the monolayer would remain intact under conditions of shear stress (104 dynes/cm2), and whether this would result in decreased platelet adherence of sheep platelets relative to nonendothelialized surfaces. The results have shown that both Biomer and Mitrathane could be endothelialized: 88.8 +/- 5.1% of the Biomer surface consisted of intact confluent endothelial cells, as did 95.45 +/- 1.7% of the Mitrathane surface. After 6 hr of shear stress, a significant reduction in this feature was observed (p = 0.02), but both materials still maintained a high percentage of confluent endothelial cells (78.65% for Biomer and 85.58% for Mitrathane). After 48 hr of shear stress, however, the percent confluence was similar to control values, which suggested new cell growth. Endothelialized Biomer compared with Mitrathane had fewer adherent single platelets, or small or large aggregates (p = 0.001, p = 0.01, and p = 0.05, respectively); this feature was not affected by shear stress. Whereas endothelialization of the surface clearly decreased platelet adherence on Mitrathane (p = 0.01), only a trend was seen with Biomer. These studies therefore show that endothelialization of these polyurethane surfaces is feasible.

[Scanning electron microscope observation on proximal enamel surfaces of normal teeth]

This observation was made on the proximal surfaces of normal permanent molars. Observations were concentrated mainly on those teeth with abraded contact areas on the mesial surface and the unabrasive distal surfaces if the partially or wholly embedded third molars. The results showed that the surfaces of the abraded contact areas were plain than those outside the contact. There were lots of pitted holes or fissures on the surfaces outside the contact areas. In the holes accumulations of bacteria could be seen. These holes and fissures could also be seen on the unexposed distal surfaces of the third molars, but no clear-defined traces of bacteria were observed in the holes.

Transcriptional control of the invariant chain gene involves promoter and enhancer elements common to and distinct from major histocompatibility complex class II genes

The invariant chain (Ii) is a glycoprotein coexpressed with the major histocompatibility complex (MHC) class II antigens. Although Ii is encoded by a single gene unlinked to the MHC gene complex, Ii and MHC class II appear to have similar patterns of tissue specific expression and generally are coordinately regulated by cytokines. Here we present evidence that transcription of the murine Ii gene is controlled by multiple cis-acting elements. The 5' regulatory region of the Ii gene appears to be combined of conserved class II regulatory elements with promoter elements commonly found in other eucaryotic genes. A region containing characteristic class II promoter elements (H box, X box, and a modified Y box) serves as an upstream enhancer in the Ii gene and might contribute to the coexpression of MHC class II and Ii genes. A series of positive control elements, the kappa B element, Sp1-binding site, and CCAAT box, are present in the Ii promoter and apparently serve distinct regulatory functions. The kappa B site in the Ii gene is a cell type-specific element, contributing to expression in a B-cell line but not in a fibroblast cell line, and the Sp1 site is required by the H-X-Y' enhancer element to stimulate promoter activity. In addition, an Ii enhancer in the first intron that specifically stimulates its own promoter has been identified. Our results suggest that a sequence match between enhancers and certain promoter elements is critical.

[Effects of proteolytic enzymes on demineralization of enamel]

Papain, trypsin and collagenase were used in the experiment for the study of their effects on the demineralization of enamel surface by organic acids in vivo. No effect of any of the enzymes was observed. The use of papain and trypsin in treating tooth surfaces in vitro, no matter whether sodium bisulfite was used, showed no effect on the demineralization of the enamel by mixed organic acids. But, by the analysis of amino acids in the enzyme solutions before and after treating tooth surface, it was shown that some proteinous substances were destroyed. Accordingly, it can be suggested that the enzyme takes no part in the destruction of the inorganic tooth substance.

Cytolysis of corneal epithelial cells by hydrogen peroxide

Superoxide radicals or products generated by these radicals in a xanthine/xanthine oxidase system lyse cultured rat and human corneal epithelial cells as measured in a chromium-51 release assay. Partial protection from this lysis is afforded by superoxide dismutase and complete protection is obtained with catalase. Hydrogen peroxide, a product of the dismutation of superoxide radicals, lyses these cells directly and is implicated as the toxic agent in the xanthine/xanthine oxidase reaction. Hydrogen peroxide also decreases cell proliferation and decreases the intact DNA. Therefore, hydrogen peroxide appears to be toxic to corneal epithelial cells. The implications of these data on the safety of hydrogen peroxide as a contact lens disinfectant are discussed.

Synthesis, characterization, and biodistribution of [113mIn]TE-BAT: a new myocardial imaging agent

In order to develop a new myocardial perfusion agent, new lipid-soluble complexes containing a net charge of +1 were evaluated. Synthesis, radiolabeling, characterization, and biodistribution of a unique indium complex, [113mIn]TE-BAT (tetraethyl-bis-aminoethanethiol), are described. The complex formation between In +3 and TE-BAT ligand is rapid, simple, and of high yield (greater than or equal to 95%). This process is amenable to kit formulation. The complex has a net charge of +1 and an In/ligand ratio of 1:1. Biodistribution in mice shows higher heart uptake and longer retention as compared to 201TI. This complex, when labeled with 111In, shows promise as a possible tracer for myocardial perfusion imaging.

[Screening for alpha-thalassemia using DNA analysis]

alpha-thalassemia was sought by gene mapping in 258 subjects selected on the basis of origin (25%), microcytosis (7%), or origin and microcytosis combined (64%). Abnormal fragments (Xba I/probe alpha) were found in 58 cases (22.5%). Using other restriction enzymes it was possible to determine the genotype alpha-/aa in 39 patients and the genotype alpha-/alpha- in 13 patients; 2 patients also exhibited hemoglobin H (alpha-/--) disease. alpha triplication anti-3.7 kb was found in 2 subjects and zeta-thalassemia in 2 other samples. 57 out of 58 patients originated from the thalassemia belt or from Africa. alpha-thalassemia is the most frequent hemoglobinopathy (21% of patients at risk) and hematologically is characterized by microcytosis. The Hb A2 level is decreased only in the alpha-/-- form of the disease. The main advantage of diagnosing zeta-thalassemias and alpha triplications lies in the possible clinical implications in the event of association with other hemoglobinopathies or beta-thalassemia.